Field of the Invention
The invention relates to a method for using narrowband performance features provided in broadband communications terminals, in broadband networks.
Broadband networks are predominantly constructed according to an asynchronous transfer mode, which is known in the specialist field as ATM and is referred to as such below. The information which is to be transferred or switched is packetized into ATM cells and is switched through the use of an ATM cell header that precedes the ATM cells. A source address and destination address are specified in the user information field of a signaling ATM cell, in which the source address represents a broadband communications terminal that initiates a connection setup and the destination address represents a broadband communications terminal to which the broadband communications terminal that initiates the connection setup is connected. Virtual path and channel information is specified in the cell headers of the ATM cells, with the path which is used by the respective connection and the virtual channel of a broadband connection being determined by that information. In the future, narrowband services will also be used and/or required in the broadband networks. Those services are, for example, a telephone service in a broadband communications terminal such as a personal computer. The performance features, such as call forwarding, etc., which are customary in narrowband networks, for example the telephone network or ISDN network, will be made available to a user of a narrowband service or narrowband function.
German Patent DE 42 24 388 C1 describes a method in which ISDN narrowband communications terminals are connected to an ISDN narrowband communications system through an ATM communications network. The narrowband user information and narrowband signaling information is transmitted cell-by-cell on dedicated connections in the ATM communications network using two network gateways. In that case, the ATM communications network is used as a feeder network for ISDN narrowband communications terminals which are to be connected to ISDN narrowband communications systems, i.e. 2.times.64 kbit/s narrowband user channels and one 16 kbit/s signaling channel.
Furthermore, European Patent Application EP 0 711 052 A1 discloses a method which can make known narrowband performance features available on a connection between broadband communications terminals leading through an ATM communications system. In order to accomplish that, the ATM communications system is connected to a narrowband communications system through an interworking unit. ATM-specific signaling information which is transferred from the ATM communications system to the interworking unit through the use of ATM cells is converted by that unit into narrowband-specific signaling information and passed on to the narrowband communications system. The narrowband communications system determines corresponding narrowband control information through the use of the received signaling information and transfers that control information back to the interworking unit. The interworking unit in turn converts the received narrowband control information into ATM-specific control information and transfers it back to the ATM communications system.